Background: Data on characteristics, comorbidities, health outcomes, and treatment patterns of patients with atrial fibrillation (AF) in Japan are scarce. The aim of this study was to address this gap in order to better understand the characteristics of Japanese AF patients.Methods and results: The 2008-2010 Japan National Health and Wellness Survey data sets were used in this study (N = 60,015). Demographics, health characteristics, stroke risk (using the CHA2DS2-VASc score), comorbidities, and health outcomes were all assessed. A total of 565 patients (0.94%) self-reported a physician diagnosis of AF. Patients with AF reported a number of comorbidities, including another cardiovascular condition (87.08%), a urological condition (67.79%), and dyspepsia (37.35%). Patients with AF also reported significantly worse health status and significantly more resource use than did controls. Based on the CHA2DS2-VASc score, most patients (88.50%) were at either moderate or high risk, yet only 64.25% of patients were currently being treated. Among those not currently treated, 42.57% had discontinued previous treatment. Among those currently treated, over a third reported nonadherent behaviors.Conclusion: Despite the disease burden and the high risk for a future stroke, not all patients are being treated according to guidelines. This treatment gap highlights the need for better therapeutic alternatives, in order to improve the management of patients with AF, in Japan.